This invention relates to a method of using an impression element to determine the actual size of a flow opening in a tubular member located in a well. More particularly, this invention relates to using an inflatable impression packer having an inflatable sleeve containing an impression element to contact a flow opening in a tubular member positioned in a well to form an extrusion representative of said flow opening and to determine the actual size of said flow opening by comparing said extrusion with calibrated test extrusion data.
In well operations and in particular oil well operations it is common practice to place a tubular member such as a well liner or casing in the well adjacent a producing formation. The tubular member is provided with relatively small fluid flow openings which are designed to permit flow of fluids from the formation into the well or from the well into the formation without permitting said or other fines to enter the well. The flow openings in the tubular member may be slots precut in the tubular member before it is positioned in the well or the flow openings may be perforations made in a tubular member after it has been run in the well. The tubular member is usually cemented into place in the well adjacent a desired formation. It is often necessary to know the actual size of the flow opening. This is particularly true when the flow opening was made by gun or jet perforation techniques after the tubular member had been positioned in the well. It is also sometimes desirable to know the actual size of a precut slot which may have been changed in size due to erosion or plugging. Heretofore impression packers have been used to obtain this type of information. It has been found, however, that an impression packer does not always give accurate information regarding hole size. The present invention is directed to determining the actual size of a flow opening located in a tubular member positioned in a well.
The present method is directed to a method of determining actual size of a flow opening in a well tubular member from an extrusion of impression material obtained by forcing the impression material into the flow opening. The inner diameter of a well tubular member having a flow opening therein is determined. The temperature in the well tubular member adjacent the flow opening is also determined. Surface test apparatus including a test tubular member having a plurality of test flow openings of different sizes formed therein is used to obtain calibrated data on flow opening size. The temperature of the test tubular member is adjusted to a value substantially equal to the well tubular member. A test inflatable impression packer having known operating characteristics and dimensions is inflated for a known pressure for a known time in the test tubular member to extrude impression material into the plurality of test flow openings to obtain a plurality of test extrusions of impression material on the test inflatable impression packer. The test inflatable impression packer is deflated and the size of said test extrusions is measured when the packer is deflated. The measured size of the test extrusions is correlated to the actual size of the test flow openings. A working inflatable impression packer having substantially the same operating characteristics and dimensions as the test inflatable impression packer is run into the well adjacent the well tubular member. The working inflatable impression packer is inflated to substantially the same pressure and for substantially the same time as the test inflatable impression packer to form a well extrusion by extruding impression material into the flow opening of the well tubular member. The working inflatable impression packer is deflated and removed from the well. The actual size of the flow opening in the well tubular member is determined by comparing the well extrusion to the data obtained by calibration of the test extrusion to actual size of the test flow openings.
A desirable embodiment of components useful in the practice of the invention include an inflatable impression packer having an inflatable sleeve containing an impression element on at least a portion of its outer surface. The inflatable packer having the inflatable sleeve containing an impression element on at least a portion of its outer surface is lowered into the well and positioned with the impression element adjacent a fluid flow opening in a tubular member which is positioned under liquid adjacent a formation penetrated by the well. The inflatable sleeve is inflated to contact the tubular member over the flow opening with the impression element at a predetermined pressure and for a predetermined time, which is normally sufficient to cause the impression element to be at least partially extruded into the opening. The sleeve is deflated to remove the impression element from contact with the tubular member. The inflatable packer is withdraw from the well and the extrusion on the impression element is compared with calibrated data of test extrusions to actual flow opening sized to determine the actual size of the flow opening in the well tubular member.